In the field of printers for labels, tags and the like, including for example, a hand operated portable label printer and dispenser such as disclosed in U.S. Pat. No. 4,081,309 which issued to the Assignee of the present invention, it is frequently desirable to provide for simultaneously printing two lines of characters. One form of two line printer includes two banks or rows of flexible endless printing bands which are supported in tandem relation, such as shown in FIG. 66 of the above patent. Preferably, each of the endless printing bands is formed by a series of pads which are integrally connected by thin flexible hinge or link portions, and the pads carry a series of raised printing characters. For example, the characters may be numerical characters or non-numeric characters such as symbols. The endless printing bands also frequently include a series of human or visually readable characters in addition to the printing characters, and the visually readable characters may be formed on relatively thinner pads which may be disposed alternately between the pads having raised printing characters.
As disclosed in U.S. Design Pat. No. 238,205 which issued to the Assignee of the present invention, a printing character may also be in the form of a code such as the universal product code used in connection with consumer products. When one group or row of printing bands is used for printing a code such as a bar code and the other group or row of endless printing bands are used for printing numerical characters which correspond to the printed code characters, it is important that the printed line of code characters correspond correctly with the printed line of numerical characters to avoid printing errors. Such errors may easily occur when the printing bands in each row are individually indexed for selecting a predetermined character. In the bar code printer disclosed in U.S. Pat. No. 4,094,244, rotary printing wheels or gears mesh with each other to avoid scribing a bar code which does not correspond to the printed numerical characters.